Although linguistic behavior is in general guided by normative rules, it need not all be rule-guided. Also, rules of language differ in their degree of constitutivity, and hence, in their force of obligation. The so-called thematic rules are characteristically of a “weak” constitutivity, and often mere regularities of usage devoid of normativity. Their possible normativity is assessed in terms of contextual-pragmatic correctnees. The thematic organization of sentences illustrates particularly well the special relationship between rule and action, those areas of linguistic behaviour where normativity may shade off into spatiotemporality. From the methodological point of view, all this requires the investigation of thematic systems as mediated through action, and further, the combining of speakers' intuitive knowledge and of observation of actual linguistic behaviour.